One of the most persistent and troublesome problems arising during conventional laundering operations is the tendency of some colored fabrics to release dye or dyes into the laundering solutions. These so-called fugitive dyes are then transferred onto other fabrics oftentimes having colors different than the fugitive dyes. This problem is commonly referred to in the an as "dye transfer". Conveniently, the coloring matter in the "dirt" on the fabrics being laundered which may likewise be transferred to other fabrics in the laundering solution is included within the meaning of dye transfer.
As is known, one way of overcoming the dye transfer problem is to complex or otherwise absorb the fugitive dyes before they have the opportunity to become attached to other fabric articles in the laundering solution. To that end, various polymers have been included in detergent compositions to inhibit dye transfer. For example, European Application No. 372 291, Jacobs et al, discloses a process for washing discoloration-sensitive textiles in which the washing or laundering solution contains several water-soluble polymers including N-vinylimidazol, N-vinyloxazolidone, N-vinylpyrrolidone and copolymers thereof to inhibit dye transfer. However, as with most detergent compositions containing dye transfer inhibiting agents, there is a tendency for such agents to decrease cleaning performance. Thus, it would be desirable to have a detergent composition containing dye transfer inhibiting agents which does not suffer from decreased cleaning performance resulting from such agents.
Also in the art of detergency, polymeric soil release agents have been used in detergent compositions to treat fabrics such that subsequently occurring stains are more easily cleaned in later laundering operations. Such polymeric soil release agents are characterized by having both hydrophilic segments, to hydrophilize the surface of hydrophobic fibers, such as polyester and nylon,and hydrophobic segments, to deposit upon hydrophobic fibers and remain adhered thereto through completion of washing and finishing cycles and thus, serve as an anchor for the hydrophilic segments. This enables subsequent stains to more easily cleaned in later washing cycles.
Typically, soil release agents comprise an oligomeric ester "backbone" and one or more "end-capping.revreaction. units. While nonionic soil release agents are known in the literature, many of the commercially important soil release agents are anionic. For example, isethionate-derived substiuents of the type OCH.sub.2 CH.sub.2 SO.sub.3 or poly-ethoxy or propoxy derivatives might be ideal and inexpensive. More specifically, U.S. Pat. No. 4,721,580, Gosselink (commonly assigned), discloses an anionic soil release agent classified as an oligomeric ester composition with end-caps having the formula NaO.sub.3 S(CH.sub.2 CH.sub.2 O).sub.n --.
However, substantial difficulties can occur due to undesirable crystallization of such soil release agents or end-capped units. In response, mixtures of sulfonate-type hydrotropes and the like with the aforementioned soil release agents have resulted in reduced crystallization problems encountered during manufacture, storage and in the laundering solution. These soil release agents, however, have not been combined with dye transfer inhibiting agents for purposes of improving cleaning performance in granular detergent compositions.
Accordingly, despite the disclosures in the art discussed above, there remains a need in the art for a granular detergent composition containing dye transfer inhibiting agents in combination with a soil release agent, together which increase cleaning performance.